CMake/Help/command/file.rst

file
----

File manipulation command.

This command is dedicated to file and path manipulation requiring access to the
filesystem.

For other path manipulation, handling only syntactic aspects, have a look at
:command:`cmake_path` command.

.. note::

  The sub-commands `RELATIVE_PATH`_, `TO_CMAKE_PATH`_ and `TO_NATIVE_PATH`_ has
  been superseded, respectively, by sub-commands
  :ref:`RELATIVE_PATH <cmake_path-RELATIVE_PATH>`,
  :ref:`CONVERT ... TO_CMAKE_PATH_LIST <cmake_path-TO_CMAKE_PATH_LIST>` and
  :ref:`CONVERT ... TO_NATIVE_PATH_LIST <cmake_path-TO_NATIVE_PATH_LIST>` of
  :command:`cmake_path` command.

Synopsis
^^^^^^^^

.. parsed-literal::

  `Reading`_
    file(`READ`_ <filename> <out-var> [...])
    file(`STRINGS`_ <filename> <out-var> [...])
    file(`\<HASH\>`_ <filename> <out-var>)
    file(`TIMESTAMP`_ <filename> <out-var> [...])
    file(`GET_RUNTIME_DEPENDENCIES`_ [...])

  `Writing`_
    file({`WRITE`_ | `APPEND`_} <filename> <content>...)
    file({`TOUCH`_ | `TOUCH_NOCREATE`_} [<file>...])
    file(`GENERATE`_ OUTPUT <output-file> [...])
    file(`CONFIGURE`_ OUTPUT <output-file> CONTENT <content> [...])

  `Filesystem`_
    file({`GLOB`_ | `GLOB_RECURSE`_} <out-var> [...] [<globbing-expr>...])
    file(`MAKE_DIRECTORY`_ [<dir>...])
    file({`REMOVE`_ | `REMOVE_RECURSE`_ } [<files>...])
    file(`RENAME`_ <oldname> <newname> [...])
    file(`COPY_FILE`_ <oldname> <newname> [...])
    file({`COPY`_ | `INSTALL`_} <file>... DESTINATION <dir> [...])
    file(`SIZE`_ <filename> <out-var>)
    file(`READ_SYMLINK`_ <linkname> <out-var>)
    file(`CREATE_LINK`_ <original> <linkname> [...])
    file(`CHMOD`_ <files>... <directories>... PERMISSIONS <permissions>... [...])
    file(`CHMOD_RECURSE`_ <files>... <directories>... PERMISSIONS <permissions>... [...])

  `Path Conversion`_
    file(`REAL_PATH`_ <path> <out-var> [BASE_DIRECTORY <dir>] [EXPAND_TILDE])
    file(`RELATIVE_PATH`_ <out-var> <directory> <file>)
    file({`TO_CMAKE_PATH`_ | `TO_NATIVE_PATH`_} <path> <out-var>)

  `Transfer`_
    file(`DOWNLOAD`_ <url> [<file>] [...])
    file(`UPLOAD`_ <file> <url> [...])

  `Locking`_
    file(`LOCK`_ <path> [...])

  `Archiving`_
    file(`ARCHIVE_CREATE`_ OUTPUT <archive> PATHS <paths>... [...])
    file(`ARCHIVE_EXTRACT`_ INPUT <archive> [...])

Reading
^^^^^^^

.. signature::
  file(READ <filename> <variable>
       [OFFSET <offset>] [LIMIT <max-in>] [HEX])

  Read content from a file called ``<filename>`` and store it in a
  ``<variable>``.  Optionally start from the given ``<offset>`` and
  read at most ``<max-in>`` bytes.  The ``HEX`` option causes data to
  be converted to a hexadecimal representation (useful for binary data).
  If the ``HEX`` option is specified, letters in the output
  (``a`` through ``f``) are in lowercase.

.. signature::
  file(STRINGS <filename> <variable> [<options>...])

  Parse a list of ASCII strings from ``<filename>`` and store it in
  ``<variable>``.  Binary data in the file are ignored.  Carriage return
  (``\r``, CR) characters are ignored.  The options are:

    ``LENGTH_MAXIMUM <max-len>``
      Consider only strings of at most a given length.

    ``LENGTH_MINIMUM <min-len>``
      Consider only strings of at least a given length.

    ``LIMIT_COUNT <max-num>``
      Limit the number of distinct strings to be extracted.

    ``LIMIT_INPUT <max-in>``
      Limit the number of input bytes to read from the file.

    ``LIMIT_OUTPUT <max-out>``
      Limit the number of total bytes to store in the ``<variable>``.

    ``NEWLINE_CONSUME``
      Treat newline characters (``\n``, LF) as part of string content
      instead of terminating at them.

    ``NO_HEX_CONVERSION``
      Intel Hex and Motorola S-record files are automatically converted to
      binary while reading unless this option is given.

    ``REGEX <regex>``
      Consider only strings that match the given regular expression,
      as described under :ref:`string(REGEX) <Regex Specification>`.

    ``ENCODING <encoding-type>``
      .. versionadded:: 3.1

      Consider strings of a given encoding.  Currently supported encodings are:
      ``UTF-8``, ``UTF-16LE``, ``UTF-16BE``, ``UTF-32LE``, ``UTF-32BE``.
      If the ``ENCODING`` option is not provided and the file
      has a Byte Order Mark, the ``ENCODING`` option will be defaulted
      to respect the Byte Order Mark.

  .. versionadded:: 3.2
    Added the ``UTF-16LE``, ``UTF-16BE``, ``UTF-32LE``, ``UTF-32BE`` encodings.

  For example, the code

  .. code-block:: cmake

    file(STRINGS myfile.txt myfile)

  stores a list in the variable ``myfile`` in which each item is a line
  from the input file.

.. signature::
  file(<HASH> <filename> <variable>)
  :target: <HASH>

  Compute a cryptographic hash of the content of ``<filename>`` and
  store it in a ``<variable>``.  The supported ``<HASH>`` algorithm names
  are those listed by the :command:`string(<HASH>)` command.

.. signature::
  file(TIMESTAMP <filename> <variable> [<format>] [UTC])

  Compute a string representation of the modification time of ``<filename>``
  and store it in ``<variable>``.  Should the command be unable to obtain a
  timestamp variable will be set to the empty string ("").

  See the :command:`string(TIMESTAMP)` command for documentation of
  the ``<format>`` and ``UTC`` options.

.. signature::
  file(GET_RUNTIME_DEPENDENCIES [...])

  .. versionadded:: 3.16

  Recursively get the list of libraries depended on by the given files:

  .. code-block:: cmake

    file(GET_RUNTIME_DEPENDENCIES
      [RESOLVED_DEPENDENCIES_VAR <deps_var>]
      [UNRESOLVED_DEPENDENCIES_VAR <unresolved_deps_var>]
      [CONFLICTING_DEPENDENCIES_PREFIX <conflicting_deps_prefix>]
      [EXECUTABLES [<executable_files>...]]
      [LIBRARIES [<library_files>...]]
      [MODULES [<module_files>...]]
      [DIRECTORIES [<directories>...]]
      [BUNDLE_EXECUTABLE <bundle_executable_file>]
      [PRE_INCLUDE_REGEXES [<regexes>...]]
      [PRE_EXCLUDE_REGEXES [<regexes>...]]
      [POST_INCLUDE_REGEXES [<regexes>...]]
      [POST_EXCLUDE_REGEXES [<regexes>...]]
      [POST_INCLUDE_FILES [<files>...]]
      [POST_EXCLUDE_FILES [<files>...]]
      )

  Please note that this sub-command is not intended to be used in project mode.
  It is intended for use at install time, either from code generated by the
  :command:`install(RUNTIME_DEPENDENCY_SET)` command, or from code provided by
  the project via :command:`install(CODE)` or :command:`install(SCRIPT)`.
  For example:

  .. code-block:: cmake

    install(CODE [[
      file(GET_RUNTIME_DEPENDENCIES
        # ...
        )
      ]])

  The arguments are as follows:

    ``RESOLVED_DEPENDENCIES_VAR <deps_var>``
      Name of the variable in which to store the list of resolved dependencies.

    ``UNRESOLVED_DEPENDENCIES_VAR <unresolved_deps_var>``
      Name of the variable in which to store the list of unresolved
      dependencies. If this variable is not specified, and there are any
      unresolved dependencies, an error is issued.

    ``CONFLICTING_DEPENDENCIES_PREFIX <conflicting_deps_prefix>``
      Variable prefix in which to store conflicting dependency information.
      Dependencies are conflicting if two files with the same name are found in
      two different directories. The list of filenames that conflict are stored
      in ``<conflicting_deps_prefix>_FILENAMES``. For each filename, the list
      of paths that were found for that filename are stored in
      ``<conflicting_deps_prefix>_<filename>``.

    ``EXECUTABLES <executable_files>``
      List of executable files to read for dependencies. These are executables
      that are typically created with :command:`add_executable`, but they do
      not have to be created by CMake. On Apple platforms, the paths to these
      files determine the value of ``@executable_path`` when recursively
      resolving the libraries. Specifying any kind of library (``STATIC``,
      ``MODULE``, or ``SHARED``) here will result in undefined behavior.

    ``LIBRARIES <library_files>``
      List of library files to read for dependencies. These are libraries that
      are typically created with :command:`add_library(SHARED)`, but they do
      not have to be created by CMake. Specifying ``STATIC`` libraries,
      ``MODULE`` libraries, or executables here will result in undefined
      behavior.

    ``MODULES <module_files>``
      List of loadable module files to read for dependencies. These are modules
      that are typically created with :command:`add_library(MODULE)`, but they
      do not have to be created by CMake. They are typically used by calling
      ``dlopen()`` at runtime rather than linked at link time with ``ld -l``.
      Specifying ``STATIC`` libraries, ``SHARED`` libraries, or executables
      here will result in undefined behavior.

    ``DIRECTORIES <directories>``
      List of additional directories to search for dependencies. On Linux
      platforms, these directories are searched if the dependency is not found
      in any of the other usual paths. If it is found in such a directory, a
      warning is issued, because it means that the file is incomplete (it does
      not list all of the directories that contain its dependencies).
      On Windows platforms, these directories are searched if the dependency
      is not found in any of the other search paths, but no warning is issued,
      because searching other paths is a normal part of Windows dependency
      resolution. On Apple platforms, this argument has no effect.

    ``BUNDLE_EXECUTABLE <bundle_executable_file>``
      Executable to treat as the "bundle executable" when resolving libraries.
      On Apple platforms, this argument determines the value of
      ``@executable_path`` when recursively resolving libraries for
      ``LIBRARIES`` and ``MODULES`` files. It has no effect on ``EXECUTABLES``
      files. On other platforms, it has no effect. This is typically (but not
      always) one of the executables in the ``EXECUTABLES`` argument which
      designates the "main" executable of the package.

  The following arguments specify filters for including or excluding libraries
  to be resolved. See below for a full description of how they work.

    ``PRE_INCLUDE_REGEXES <regexes>``
      List of pre-include regexes through which to filter the names of
      not-yet-resolved dependencies.

    ``PRE_EXCLUDE_REGEXES <regexes>``
      List of pre-exclude regexes through which to filter the names of
      not-yet-resolved dependencies.

    ``POST_INCLUDE_REGEXES <regexes>``
      List of post-include regexes through which to filter the names of
      resolved dependencies.

    ``POST_EXCLUDE_REGEXES <regexes>``
      List of post-exclude regexes through which to filter the names of
      resolved dependencies.

    ``POST_INCLUDE_FILES <files>``
      .. versionadded:: 3.21

      List of post-include filenames through which to filter the names of
      resolved dependencies. Symlinks are resolved when attempting to match
      these filenames.

    ``POST_EXCLUDE_FILES <files>``
      .. versionadded:: 3.21

      List of post-exclude filenames through which to filter the names of
      resolved dependencies. Symlinks are resolved when attempting to match
      these filenames.

  These arguments can be used to exclude unwanted system libraries when
  resolving the dependencies, or to include libraries from a specific
  directory. The filtering works as follows:

  1. If the not-yet-resolved dependency matches any of the
     ``PRE_INCLUDE_REGEXES``, steps 2 and 3 are skipped, and the dependency
     resolution proceeds to step 4.

  2. If the not-yet-resolved dependency matches any of the
     ``PRE_EXCLUDE_REGEXES``, dependency resolution stops for that dependency.

  3. Otherwise, dependency resolution proceeds.

  4. ``file(GET_RUNTIME_DEPENDENCIES)`` searches for the dependency according
     to the linking rules of the platform (see below).

  5. If the dependency is found, and its full path matches one of the
     ``POST_INCLUDE_REGEXES`` or ``POST_INCLUDE_FILES``, the full path is added
     to the resolved dependencies, and ``file(GET_RUNTIME_DEPENDENCIES)``
     recursively resolves that library's own dependencies. Otherwise, resolution
     proceeds to step 6.

  6. If the dependency is found, but its full path matches one of the
     ``POST_EXCLUDE_REGEXES`` or ``POST_EXCLUDE_FILES``, it is not added to the
     resolved dependencies, and dependency resolution stops for that dependency.

  7. If the dependency is found, and its full path does not match either
     ``POST_INCLUDE_REGEXES``, ``POST_INCLUDE_FILES``, ``POST_EXCLUDE_REGEXES``,
     or ``POST_EXCLUDE_FILES``, the full path is added to the resolved
     dependencies, and ``file(GET_RUNTIME_DEPENDENCIES)``  recursively resolves
     that library's own dependencies.

  Different platforms have different rules for how dependencies are resolved.
  These specifics are described here.

  On Linux platforms, library resolution works as follows:

  1. If the depending file does not have any ``RUNPATH`` entries, and the
     library exists in one of the depending file's ``RPATH`` entries, or its
     parents', in that order, the dependency is resolved to that file.
  2. Otherwise, if the depending file has any ``RUNPATH`` entries, and the
     library exists in one of those entries, the dependency is resolved to that
     file.
  3. Otherwise, if the library exists in one of the directories listed by
     ``ldconfig``, the dependency is resolved to that file.
  4. Otherwise, if the library exists in one of the ``DIRECTORIES`` entries,
     the dependency is resolved to that file. In this case, a warning is
     issued, because finding a file in one of the ``DIRECTORIES`` means that
     the depending file is not complete (it does not list all the directories
     from which it pulls dependencies).

  5. Otherwise, the dependency is unresolved.

  On Windows platforms, library resolution works as follows:

  1. The dependent DLL name is converted to lowercase. Windows DLL names are
     case-insensitive, and some linkers mangle the case of the DLL dependency
     names. However, this makes it more difficult for ``PRE_INCLUDE_REGEXES``,
     ``PRE_EXCLUDE_REGEXES``, ``POST_INCLUDE_REGEXES``, and
     ``POST_EXCLUDE_REGEXES`` to properly filter DLL names - every regex would
     have to check for both uppercase and lowercase letters. For example:

     .. code-block:: cmake

       file(GET_RUNTIME_DEPENDENCIES
         # ...
         PRE_INCLUDE_REGEXES "^[Mm][Yy][Ll][Ii][Bb][Rr][Aa][Rr][Yy]\\.[Dd][Ll][Ll]$"
         )

     Converting the DLL name to lowercase allows the regexes to only match
     lowercase names, thus simplifying the regex. For example:

     .. code-block:: cmake

       file(GET_RUNTIME_DEPENDENCIES
         # ...
         PRE_INCLUDE_REGEXES "^mylibrary\\.dll$"
         )

     This regex will match ``mylibrary.dll`` regardless of how it is cased,
     either on disk or in the depending file. (For example, it will match
     ``mylibrary.dll``, ``MyLibrary.dll``, and ``MYLIBRARY.DLL``.)

     Please note that the directory portion of any resolved DLLs retains its
     casing and is not converted to lowercase. Only the filename portion is
     converted.

  2. (**Not yet implemented**) If the depending file is a Windows Store app,
     and the dependency is listed as a dependency in the application's package
     manifest, the dependency is resolved to that file.

  3. Otherwise, if the library exists in the same directory as the depending
     file, the dependency is resolved to that file.

  4. Otherwise, if the library exists in either the operating system's
     ``system32`` directory or the ``Windows`` directory, in that order, the
     dependency is resolved to that file.

  5. Otherwise, if the library exists in one of the directories specified by
     ``DIRECTORIES``, in the order they are listed, the dependency is resolved
     to that file. In this case, a warning is not issued, because searching
     other directories is a normal part of Windows library resolution.

  6. Otherwise, the dependency is unresolved.

  On Apple platforms, library resolution works as follows:

  1. If the dependency starts with ``@executable_path/``, and an
     ``EXECUTABLES`` argument is in the process of being resolved, and
     replacing ``@executable_path/`` with the directory of the executable
     yields an existing file, the dependency is resolved to that file.

  2. Otherwise, if the dependency starts with ``@executable_path/``, and there
     is a ``BUNDLE_EXECUTABLE`` argument, and replacing ``@executable_path/``
     with the directory of the bundle executable yields an existing file, the
     dependency is resolved to that file.

  3. Otherwise, if the dependency starts with ``@loader_path/``, and replacing
     ``@loader_path/`` with the directory of the depending file yields an
     existing file, the dependency is resolved to that file.

  4. Otherwise, if the dependency starts with ``@rpath/``, and replacing
     ``@rpath/`` with one of the ``RPATH`` entries of the depending file
     yields an existing file, the dependency is resolved to that file.
     Note that ``RPATH`` entries that start with ``@executable_path/`` or
     ``@loader_path/`` also have these items replaced with the appropriate
     path.

  5. Otherwise, if the dependency is an absolute file that exists,
     the dependency is resolved to that file.

  6. Otherwise, the dependency is unresolved.

  This function accepts several variables that determine which tool is used for
  dependency resolution:

  .. variable:: CMAKE_GET_RUNTIME_DEPENDENCIES_PLATFORM

    Determines which operating system and executable format the files are built
    for. This could be one of several values:

    * ``linux+elf``
    * ``windows+pe``
    * ``macos+macho``

    If this variable is not specified, it is determined automatically by system
    introspection.

  .. variable:: CMAKE_GET_RUNTIME_DEPENDENCIES_TOOL

    Determines the tool to use for dependency resolution. It could be one of
    several values, depending on the value of
    :variable:`CMAKE_GET_RUNTIME_DEPENDENCIES_PLATFORM`:

    ================================================= =============================================
       ``CMAKE_GET_RUNTIME_DEPENDENCIES_PLATFORM``       ``CMAKE_GET_RUNTIME_DEPENDENCIES_TOOL``
    ================================================= =============================================
    ``linux+elf``                                     ``objdump``
    ``windows+pe``                                    ``objdump`` or ``dumpbin``
    ``macos+macho``                                   ``otool``
    ================================================= =============================================

    If this variable is not specified, it is determined automatically by system
    introspection.

  .. variable:: CMAKE_GET_RUNTIME_DEPENDENCIES_COMMAND

    Determines the path to the tool to use for dependency resolution. This is
    the actual path to ``objdump``, ``dumpbin``, or ``otool``.

    If this variable is not specified, it is determined by the value of
    ``CMAKE_OBJDUMP`` if set, else by system introspection.

    .. versionadded:: 3.18
      Use ``CMAKE_OBJDUMP`` if set.

Writing
^^^^^^^

.. signature::
  file(WRITE <filename> <content>...)
  file(APPEND <filename> <content>...)

  Write ``<content>`` into a file called ``<filename>``.  If the file does
  not exist, it will be created.  If the file already exists, ``WRITE``
  mode will overwrite it and ``APPEND`` mode will append to the end.
  Any directories in the path specified by ``<filename>`` that do not
  exist will be created.

  If the file is a build input, use the :command:`configure_file` command
  to update the file only when its content changes.

.. signature::
  file(TOUCH [<files>...])
  file(TOUCH_NOCREATE [<files>...])

  .. versionadded:: 3.12

  Create a file with no content if it does not yet exist. If the file already
  exists, its access and/or modification will be updated to the time when the
  function call is executed.

  Use ``TOUCH_NOCREATE`` to touch a file if it exists but not create it.
  If a file does not exist it will be silently ignored.

  With ``TOUCH`` and ``TOUCH_NOCREATE``, the contents of an existing file
  will not be modified.

.. signature::
  file(GENERATE [...])

  Generate an output file for each build configuration supported by the current
  :manual:`CMake Generator <cmake-generators(7)>`.  Evaluate
  :manual:`generator expressions <cmake-generator-expressions(7)>`
  from the input content to produce the output content.

  .. code-block:: cmake

    file(GENERATE OUTPUT <output-file>
         <INPUT <input-file>|CONTENT <content>>
         [CONDITION <expression>] [TARGET <target>]
         [NO_SOURCE_PERMISSIONS | USE_SOURCE_PERMISSIONS |
          FILE_PERMISSIONS <permissions>...]
         [NEWLINE_STYLE [UNIX|DOS|WIN32|LF|CRLF] ])

  The options are:

    ``CONDITION <condition>``
      Generate the output file for a particular configuration only if
      the condition is true.  The condition must be either ``0`` or ``1``
      after evaluating generator expressions.

    ``CONTENT <content>``
      Use the content given explicitly as input.

    ``INPUT <input-file>``
      Use the content from a given file as input.

      .. versionchanged:: 3.10
        A relative path is treated with respect to the value of
        :variable:`CMAKE_CURRENT_SOURCE_DIR`.  See policy :policy:`CMP0070`.

    ``OUTPUT <output-file>``
      Specify the output file name to generate.  Use generator expressions
      such as :genex:`$<CONFIG>` to specify a configuration-specific
      output file name.  Multiple configurations may generate the same output
      file only if the generated content is identical.  Otherwise, the
      ``<output-file>`` must evaluate to an unique name for each configuration.

      .. versionchanged:: 3.10
        A relative path (after evaluating generator expressions) is treated
        with respect to the value of :variable:`CMAKE_CURRENT_BINARY_DIR`.
        See policy :policy:`CMP0070`.

    ``TARGET <target>``
      .. versionadded:: 3.19

      Specify which target to use when evaluating generator expressions that
      require a target for evaluation (e.g.
      :genex:`$<COMPILE_FEATURES:...>`,
      :genex:`$<TARGET_PROPERTY:prop>`).

    ``NO_SOURCE_PERMISSIONS``
      .. versionadded:: 3.20

      The generated file permissions default to the standard 644 value
      (-rw-r--r--).

    ``USE_SOURCE_PERMISSIONS``
      .. versionadded:: 3.20

      Transfer the file permissions of the ``INPUT`` file to the generated
      file. This is already the default behavior if none of the three
      permissions-related keywords are given (``NO_SOURCE_PERMISSIONS``,
      ``USE_SOURCE_PERMISSIONS`` or ``FILE_PERMISSIONS``).  The
      ``USE_SOURCE_PERMISSIONS`` keyword mostly serves as a way of making
      the intended behavior clearer at the call site. It is an error to
      specify this option without ``INPUT``.

    ``FILE_PERMISSIONS <permissions>...``
      .. versionadded:: 3.20

      Use the specified permissions for the generated file.

    ``NEWLINE_STYLE <style>``
      .. versionadded:: 3.20

      Specify the newline style for the generated file.  Specify
      ``UNIX`` or ``LF`` for ``\n`` newlines, or specify
      ``DOS``, ``WIN32``, or ``CRLF`` for ``\r\n`` newlines.

  Exactly one ``CONTENT`` or ``INPUT`` option must be given.  A specific
  ``OUTPUT`` file may be named by at most one invocation of ``file(GENERATE)``.
  Generated files are modified and their timestamp updated on subsequent cmake
  runs only if their content is changed.

  Note also that ``file(GENERATE)`` does not create the output file until the
  generation phase. The output file will not yet have been written when the
  ``file(GENERATE)`` command returns, it is written only after processing all
  of a project's ``CMakeLists.txt`` files.

.. signature::
  file(CONFIGURE OUTPUT <output-file>
       CONTENT <content>
       [ESCAPE_QUOTES] [@ONLY]
       [NEWLINE_STYLE [UNIX|DOS|WIN32|LF|CRLF] ])
  :target: CONFIGURE

  .. versionadded:: 3.18

  Generate an output file using the input given by ``CONTENT`` and substitute
  variable values referenced as ``@VAR@`` or ``${VAR}`` contained therein. The
  substitution rules behave the same as the :command:`configure_file` command.
  In order to match :command:`configure_file`'s behavior, generator expressions
  are not supported for both ``OUTPUT`` and ``CONTENT``.

  The arguments are:

    ``OUTPUT <output-file>``
      Specify the output file name to generate. A relative path is treated with
      respect to the value of :variable:`CMAKE_CURRENT_BINARY_DIR`.
      ``<output-file>`` does not support generator expressions.

    ``CONTENT <content>``
      Use the content given explicitly as input.
      ``<content>`` does not support generator expressions.

    ``ESCAPE_QUOTES``
      Escape any substituted quotes with backslashes (C-style).

    ``@ONLY``
      Restrict variable replacement to references of the form ``@VAR@``.
      This is useful for configuring scripts that use ``${VAR}`` syntax.

    ``NEWLINE_STYLE <style>``
      Specify the newline style for the output file.  Specify
      ``UNIX`` or ``LF`` for ``\n`` newlines, or specify
      ``DOS``, ``WIN32``, or ``CRLF`` for ``\r\n`` newlines.

Filesystem
^^^^^^^^^^

.. signature::
  file(GLOB <variable>
       [LIST_DIRECTORIES true|false] [RELATIVE <path>] [CONFIGURE_DEPENDS]
       [<globbing-expressions>...])
  file(GLOB_RECURSE <variable> [FOLLOW_SYMLINKS]
       [LIST_DIRECTORIES true|false] [RELATIVE <path>] [CONFIGURE_DEPENDS]
       [<globbing-expressions>...])

  Generate a list of files that match the ``<globbing-expressions>`` and
  store it into the ``<variable>``.  Globbing expressions are similar to
  regular expressions, but much simpler.  If ``RELATIVE`` flag is
  specified, the results will be returned as relative paths to the given
  path.

  .. versionchanged:: 3.6
    The results will be ordered lexicographically.

  On Windows and macOS, globbing is case-insensitive even if the underlying
  filesystem is case-sensitive (both filenames and globbing expressions are
  converted to lowercase before matching).  On other platforms, globbing is
  case-sensitive.

  .. versionadded:: 3.3
    By default ``GLOB`` lists directories. Directories are omitted in the
    result if ``LIST_DIRECTORIES`` is set to false.

  .. versionadded:: 3.12
    If the ``CONFIGURE_DEPENDS`` flag is specified, CMake will add logic
    to the main build system check target to rerun the flagged ``GLOB``
    commands at build time. If any of the outputs change, CMake will regenerate
    the build system.

  .. note::
    We do not recommend using GLOB to collect a list of source files from
    your source tree.  If no CMakeLists.txt file changes when a source is
    added or removed then the generated build system cannot know when to
    ask CMake to regenerate.
    The ``CONFIGURE_DEPENDS`` flag may not work reliably on all generators, or
    if a new generator is added in the future that cannot support it, projects
    using it will be stuck. Even if ``CONFIGURE_DEPENDS`` works reliably, there
    is still a cost to perform the check on every rebuild.

  Examples of globbing expressions include:

  ============== ======================================================
  ``*.cxx``      match all files with extension ``cxx``
  ``*.vt?``      match all files with extension ``vta``, ..., ``vtz``
  ``f[3-5].txt`` match files ``f3.txt``, ``f4.txt``, ``f5.txt``
  ============== ======================================================

  The ``GLOB_RECURSE`` mode will traverse all the subdirectories of the
  matched directory and match the files.  Subdirectories that are symlinks
  are only traversed if ``FOLLOW_SYMLINKS`` is given or policy
  :policy:`CMP0009` is not set to ``NEW``.

  .. versionadded:: 3.3
    By default ``GLOB_RECURSE`` omits directories from result list. Setting
    ``LIST_DIRECTORIES`` to true adds directories to result list.
    If ``FOLLOW_SYMLINKS`` is given or policy :policy:`CMP0009` is not set to
    ``NEW`` then ``LIST_DIRECTORIES`` treats symlinks as directories.

  Examples of recursive globbing include:

  ============== ======================================================
  ``/dir/*.py``  match all python files in ``/dir`` and subdirectories
  ============== ======================================================

.. signature::
  file(MAKE_DIRECTORY [<directories>...])

  Create the given directories and their parents as needed.

.. signature::
  file(REMOVE [<files>...])
  file(REMOVE_RECURSE [<files>...])

  Remove the given files.  The ``REMOVE_RECURSE`` mode will remove the given
  files and directories, including non-empty directories. No error is emitted
  if a given file does not exist.  Relative input paths are evaluated with
  respect to the current source directory.

  .. versionchanged:: 3.15
    Empty input paths are ignored with a warning.  Previous versions of CMake
    interpreted empty strings as a relative path with respect to the current
    directory and removed its contents.

.. signature::
  file(RENAME <oldname> <newname> [RESULT <result>] [NO_REPLACE])

  Move a file or directory within a filesystem from ``<oldname>`` to
  ``<newname>``, replacing the destination atomically.

  The options are:

    ``RESULT <result>``
      .. versionadded:: 3.21

      Set ``<result>`` variable to ``0`` on success or an error message
      otherwise. If ``RESULT`` is not specified and the operation fails,
      an error is emitted.

    ``NO_REPLACE``
      .. versionadded:: 3.21

      If the ``<newname>`` path already exists, do not replace it.
      If ``RESULT <result>`` is used, the result variable will be
      set to ``NO_REPLACE``.  Otherwise, an error is emitted.

.. signature::
  file(COPY_FILE <oldname> <newname>
       [RESULT <result>]
       [ONLY_IF_DIFFERENT]
       [INPUT_MAY_BE_RECENT])

  .. versionadded:: 3.21

  Copy a file from ``<oldname>`` to ``<newname>``. Directories are not
  supported. Symlinks are ignored and ``<oldfile>``'s content is read and
  written to ``<newname>`` as a new file.

  The options are:

    ``RESULT <result>``
      Set ``<result>`` variable to ``0`` on success or an error message
      otherwise.  If ``RESULT`` is not specified and the operation fails,
      an error is emitted.

    ``ONLY_IF_DIFFERENT``
      If the ``<newname>`` path already exists, do not replace it if the file's
      contents are already the same as ``<oldname>`` (this avoids updating
      ``<newname>``'s timestamp).

    ``INPUT_MAY_BE_RECENT``
      .. versionadded:: 3.26

      Tell CMake that the input file may have been recently created.  This is
      meaningful only on Windows, where files may be inaccessible for a short
      time after they are created.  With this option, if permission is denied,
      CMake will retry reading the input a few times.

  This sub-command has some similarities to :command:`configure_file`
  with the ``COPYONLY`` option.  An important difference is that
  :command:`configure_file` creates a dependency on the source file,
  so CMake will be re-run if it changes. The ``file(COPY_FILE)``
  sub-command does not create such a dependency.

  See also the :command:`file(COPY)` sub-command just below which provides
  further file-copying capabilities.

.. signature::
  file(COPY [...])
  file(INSTALL [...])

  The ``COPY`` signature copies files, directories, and symlinks to a
  destination folder.  Relative input paths are evaluated with respect
  to the current source directory, and a relative destination is
  evaluated with respect to the current build directory.  Copying
  preserves input file timestamps, and optimizes out a file if it exists
  at the destination with the same timestamp.  Copying preserves input
  permissions unless explicit permissions or ``NO_SOURCE_PERMISSIONS``
  are given (default is ``USE_SOURCE_PERMISSIONS``).

  .. code-block:: cmake

    file(<COPY|INSTALL> <files>... DESTINATION <dir>
         [NO_SOURCE_PERMISSIONS | USE_SOURCE_PERMISSIONS]
         [FILE_PERMISSIONS <permissions>...]
         [DIRECTORY_PERMISSIONS <permissions>...]
         [FOLLOW_SYMLINK_CHAIN]
         [FILES_MATCHING]
         [[PATTERN <pattern> | REGEX <regex>]
          [EXCLUDE] [PERMISSIONS <permissions>...]] [...])

  .. note::

    For a simple file copying operation, the :command:`file(COPY_FILE)`
    sub-command just above may be easier to use.

  .. versionadded:: 3.15
    If ``FOLLOW_SYMLINK_CHAIN`` is specified, ``COPY`` will recursively resolve
    the symlinks at the paths given until a real file is found, and install
    a corresponding symlink in the destination for each symlink encountered.
    For each symlink that is installed, the resolution is stripped of the
    directory, leaving only the filename, meaning that the new symlink points
    to a file in the same directory as the symlink. This feature is useful on
    some Unix systems, where libraries are installed as a chain of symlinks
    with version numbers, with less specific versions pointing to more specific
    versions. ``FOLLOW_SYMLINK_CHAIN`` will install all of these symlinks and
    the library itself into the destination directory. For example, if you have
    the following directory structure:

      * ``/opt/foo/lib/libfoo.so.1.2.3``
      * ``/opt/foo/lib/libfoo.so.1.2 -> libfoo.so.1.2.3``
      * ``/opt/foo/lib/libfoo.so.1 -> libfoo.so.1.2``
      * ``/opt/foo/lib/libfoo.so -> libfoo.so.1``

    and you do:

    .. code-block:: cmake

      file(COPY /opt/foo/lib/libfoo.so DESTINATION lib FOLLOW_SYMLINK_CHAIN)

    This will install all of the symlinks and ``libfoo.so.1.2.3`` itself into
    ``lib``.

  See the :command:`install(DIRECTORY)` command for documentation of
  permissions, ``FILES_MATCHING``, ``PATTERN``, ``REGEX``, and
  ``EXCLUDE`` options.  Copying directories preserves the structure
  of their content even if options are used to select a subset of
  files.

  The ``INSTALL`` signature differs slightly from ``COPY``: it prints
  status messages, and ``NO_SOURCE_PERMISSIONS`` is default. Installation
  scripts generated by the :command:`install` command use this signature
  (with some undocumented options for internal use).

  .. versionchanged:: 3.22

    The environment variable :envvar:`CMAKE_INSTALL_MODE` can override the
    default copying behavior of :command:`file(INSTALL)`.

.. signature::
  file(SIZE <filename> <variable>)

  .. versionadded:: 3.14

  Determine the file size of the ``<filename>`` and put the result in
  ``<variable>`` variable. Requires that ``<filename>`` is a valid path
  pointing to a file and is readable.

.. signature::
  file(READ_SYMLINK <linkname> <variable>)

  .. versionadded:: 3.14

  Query the symlink ``<linkname>`` and stores the path it points to
  in the result ``<variable>``.  If ``<linkname>`` does not exist
  or is not a symlink, CMake issues a fatal error.

  Note that this command returns the raw symlink path and does not resolve
  a relative path.  The following is an example of how to ensure that an
  absolute path is obtained:

  .. code-block:: cmake

    set(linkname "/path/to/foo.sym")
    file(READ_SYMLINK "${linkname}" result)
    if(NOT IS_ABSOLUTE "${result}")
      get_filename_component(dir "${linkname}" DIRECTORY)
      set(result "${dir}/${result}")
    endif()

.. signature::
  file(CREATE_LINK <original> <linkname>
       [RESULT <result>] [COPY_ON_ERROR] [SYMBOLIC])

  .. versionadded:: 3.14

  Create a link ``<linkname>`` that points to ``<original>``.
  It will be a hard link by default, but providing the ``SYMBOLIC`` option
  results in a symbolic link instead.  Hard links require that ``original``
  exists and is a file, not a directory.  If ``<linkname>`` already exists,
  it will be overwritten.

  The ``<result>`` variable, if specified, receives the status of the
  operation.  It is set to ``0`` upon success or an error message otherwise.
  If ``RESULT`` is not specified and the operation fails, a fatal error is
  emitted.

  Specifying ``COPY_ON_ERROR`` enables copying the file as a fallback if
  creating the link fails.  It can be useful for handling situations such as
  ``<original>`` and ``<linkname>`` being on different drives or mount points,
  which would make them unable to support a hard link.

.. signature::
  file(CHMOD <files>... <directories>...
       [PERMISSIONS <permissions>...]
       [FILE_PERMISSIONS <permissions>...]
       [DIRECTORY_PERMISSIONS <permissions>...])

  .. versionadded:: 3.19

  Set the permissions for the ``<files>...`` and ``<directories>...``
  specified. Valid permissions are  ``OWNER_READ``, ``OWNER_WRITE``,
  ``OWNER_EXECUTE``, ``GROUP_READ``, ``GROUP_WRITE``, ``GROUP_EXECUTE``,
  ``WORLD_READ``, ``WORLD_WRITE``, ``WORLD_EXECUTE``, ``SETUID``, ``SETGID``.

  Valid combination of keywords are:

    ``PERMISSIONS``
      All items are changed.

    ``FILE_PERMISSIONS``
      Only files are changed.

    ``DIRECTORY_PERMISSIONS``
      Only directories are changed.

    ``PERMISSIONS`` and ``FILE_PERMISSIONS``
      ``FILE_PERMISSIONS`` overrides ``PERMISSIONS`` for files.

    ``PERMISSIONS`` and ``DIRECTORY_PERMISSIONS``
      ``DIRECTORY_PERMISSIONS`` overrides ``PERMISSIONS`` for directories.

    ``FILE_PERMISSIONS`` and ``DIRECTORY_PERMISSIONS``
      Use ``FILE_PERMISSIONS`` for files and ``DIRECTORY_PERMISSIONS`` for
      directories.

.. signature::
  file(CHMOD_RECURSE <files>... <directories>...
       [PERMISSIONS <permissions>...]
       [FILE_PERMISSIONS <permissions>...]
       [DIRECTORY_PERMISSIONS <permissions>...])

  .. versionadded:: 3.19

  Same as :cref:`CHMOD`, but change the permissions of files and directories
  present in the ``<directories>...`` recursively.


Path Conversion
^^^^^^^^^^^^^^^

.. signature::
  file(REAL_PATH <path> <out-var> [BASE_DIRECTORY <dir>] [EXPAND_TILDE])

  .. versionadded:: 3.19

  Compute the absolute path to an existing file or directory with symlinks
  resolved.  The options are:

    ``BASE_DIRECTORY <dir>``
      If the provided ``<path>`` is a relative path, it is evaluated relative
      to the given base directory ``<dir>``. If no base directory is provided,
      the default base directory will be :variable:`CMAKE_CURRENT_SOURCE_DIR`.

    ``EXPAND_TILDE``
      .. versionadded:: 3.21

      If the ``<path>`` is ``~`` or starts with ``~/``, the ``~`` is replaced
      by the user's home directory.  The path to the home directory is obtained
      from environment variables.  On Windows, the ``USERPROFILE`` environment
      variable is used, falling back to the ``HOME`` environment variable
      if ``USERPROFILE`` is not defined.  On all other platforms, only ``HOME``
      is used.

.. signature::
  file(RELATIVE_PATH <variable> <directory> <file>)

  Compute the relative path from a ``<directory>`` to a ``<file>`` and
  store it in the ``<variable>``.

.. signature::
  file(TO_CMAKE_PATH "<path>" <variable>)
  file(TO_NATIVE_PATH "<path>" <variable>)

  The ``TO_CMAKE_PATH`` mode converts a native ``<path>`` into a cmake-style
  path with forward-slashes (``/``).  The input can be a single path or a
  system search path like ``$ENV{PATH}``.  A search path will be converted
  to a cmake-style list separated by ``;`` characters.

  The ``TO_NATIVE_PATH`` mode converts a cmake-style ``<path>`` into a native
  path with platform-specific slashes (``\`` on Windows hosts and ``/``
  elsewhere).

  Always use double quotes around the ``<path>`` to be sure it is treated
  as a single argument to this command.

Transfer
^^^^^^^^

.. signature::
  file(DOWNLOAD <url> [<file>] [<options>...])
  file(UPLOAD <file> <url> [<options>...])

  The ``DOWNLOAD`` subcommand downloads the given ``<url>`` to a local
  ``<file>``.  The ``UPLOAD`` mode uploads a local ``<file>`` to a given
  ``<url>``.

  .. versionadded:: 3.19
    If ``<file>`` is not specified for ``file(DOWNLOAD)``, the file is not
    saved. This can be useful if you want to know if a file can be downloaded
    (for example, to check that it exists) without actually saving it anywhere.

  Options to both ``DOWNLOAD`` and ``UPLOAD`` are:

    ``INACTIVITY_TIMEOUT <seconds>``
      Terminate the operation after a period of inactivity.

    ``LOG <variable>``
      Store a human-readable log of the operation in a variable.

    ``SHOW_PROGRESS``
      Print progress information as status messages until the operation is
      complete.

    ``STATUS <variable>``
      Store the resulting status of the operation in a variable.
      The status is a ``;`` separated list of length 2.
      The first element is the numeric return value for the operation,
      and the second element is a string value for the error.
      A ``0`` numeric error means no error in the operation.

    ``TIMEOUT <seconds>``
      Terminate the operation after a given total time has elapsed.

    ``USERPWD <username>:<password>``
      .. versionadded:: 3.7

      Set username and password for operation.

    ``HTTPHEADER <HTTP-header>``
      .. versionadded:: 3.7

      HTTP header for ``DOWNLOAD`` and ``UPLOAD`` operations. ``HTTPHEADER``
      can be repeated for multiple options:

      .. code-block:: cmake

        file(DOWNLOAD <url>
             HTTPHEADER "Authorization: Bearer <auth-token>"
             HTTPHEADER "UserAgent: Mozilla/5.0")

    ``NETRC <level>``
      .. versionadded:: 3.11

      Specify whether the .netrc file is to be used for operation.  If this
      option is not specified, the value of the :variable:`CMAKE_NETRC`
      variable will be used instead.

      Valid levels are:

        ``IGNORED``
          The .netrc file is ignored.
          This is the default.

        ``OPTIONAL``
          The .netrc file is optional, and information in the URL is preferred.
          The file will be scanned to find which ever information is not
          specified in the URL.

        ``REQUIRED``
          The .netrc file is required, and information in the URL is ignored.

    ``NETRC_FILE <file>``
      .. versionadded:: 3.11

      Specify an alternative .netrc file to the one in your home directory,
      if the ``NETRC`` level is ``OPTIONAL`` or ``REQUIRED``. If this option
      is not specified, the value of the :variable:`CMAKE_NETRC_FILE` variable
      will be used instead.

    ``TLS_VERIFY <ON|OFF>``
      Specify whether to verify the server certificate for ``https://`` URLs.
      The default is to *not* verify. If this option is not specified, the
      value of the :variable:`CMAKE_TLS_VERIFY` variable will be used instead.

      .. versionadded:: 3.18
        Added support to ``file(UPLOAD)``.

    ``TLS_CAINFO <file>``
      Specify a custom Certificate Authority file for ``https://`` URLs.
      If this option is not specified, the value of the
      :variable:`CMAKE_TLS_CAINFO` variable will be used instead.

      .. versionadded:: 3.18
        Added support to ``file(UPLOAD)``.

  For ``https://`` URLs CMake must be built with OpenSSL support.  ``TLS/SSL``
  certificates are not checked by default.  Set ``TLS_VERIFY`` to ``ON`` to
  check certificates.

  Additional options to ``DOWNLOAD`` are:

    ``EXPECTED_HASH <algorithm>=<value>``
      Verify that the downloaded content hash matches the expected value, where
      ``<algorithm>`` is one of the algorithms supported by :cref:`<HASH>`.
      If the file already exists and matches the hash, the download is skipped.
      If the file already exists and does not match the hash, the file is
      downloaded again. If after download the file does not match the hash, the
      operation fails with an error. It is an error to specify this option if
      ``DOWNLOAD`` is not given a ``<file>``.

    ``EXPECTED_MD5 <value>``
      Historical short-hand for ``EXPECTED_HASH MD5=<value>``. It is an error
      to specify this if ``DOWNLOAD`` is not given a ``<file>``.

    ``RANGE_START <value>``
      .. versionadded:: 3.24

      Offset of the start of the range in file in bytes. Could be omitted to
      download up to the specified ``RANGE_END``.

    ``RANGE_END <value>``
      .. versionadded:: 3.24

      Offset of the end of the range in file in bytes. Could be omitted to
      download everything from the specified ``RANGE_START`` to the end of
      file.

Locking
^^^^^^^

.. signature::
  file(LOCK <path> [DIRECTORY] [RELEASE]
       [GUARD <FUNCTION|FILE|PROCESS>]
       [RESULT_VARIABLE <variable>]
       [TIMEOUT <seconds>])

  .. versionadded:: 3.2

  Lock a file specified by ``<path>`` if no ``DIRECTORY`` option present and
  file ``<path>/cmake.lock`` otherwise.  The file will be locked for the scope
  defined by the ``GUARD`` option (default value is ``PROCESS``).  The
  ``RELEASE`` option can be used to unlock the file explicitly.  If the
  ``TIMEOUT`` option is not specified, CMake will wait until the lock succeeds
  or until a fatal error occurs.  If ``TIMEOUT`` is set to ``0``, locking will
  be tried once and the result will be reported immediately.  If ``TIMEOUT``
  is not ``0``, CMake will try to lock the file for the period specified by
  the ``TIMEOUT <seconds>`` value.  Any errors will be interpreted as fatal if
  there is no ``RESULT_VARIABLE`` option.  Otherwise, the result will be stored
  in ``<variable>`` and will be ``0`` on success or an error message on
  failure.

  Note that lock is advisory; there is no guarantee that other processes will
  respect this lock, i.e. lock synchronize two or more CMake instances sharing
  some modifiable resources. Similar logic applies to the ``DIRECTORY`` option;
  locking a parent directory doesn't prevent other ``LOCK`` commands from
  locking any child directory or file.

  Trying to lock the same file twice is not allowed.  Any intermediate
  directories and the file itself will be created if they not exist.  The
  ``GUARD`` and ``TIMEOUT`` options are ignored on the ``RELEASE`` operation.

Archiving
^^^^^^^^^

.. signature::
  file(ARCHIVE_CREATE OUTPUT <archive>
    PATHS <paths>...
    [FORMAT <format>]
    [COMPRESSION <compression>
     [COMPRESSION_LEVEL <compression-level>]]
    [MTIME <mtime>]
    [VERBOSE])
  :target: ARCHIVE_CREATE
  :break: verbatim

  .. versionadded:: 3.18

  Creates the specified ``<archive>`` file with the files and directories
  listed in ``<paths>``.  Note that ``<paths>`` must list actual files or
  directories; wildcards are not supported.

  Use the ``FORMAT`` option to specify the archive format.  Supported values
  for ``<format>`` are ``7zip``, ``gnutar``, ``pax``, ``paxr``, ``raw`` and
  ``zip``.  If ``FORMAT`` is not given, the default format is ``paxr``.

  Some archive formats allow the type of compression to be specified.
  The ``7zip`` and ``zip`` archive formats already imply a specific type of
  compression.  The other formats use no compression by default, but can be
  directed to do so with the ``COMPRESSION`` option.  Valid values for
  ``<compression>`` are ``None``, ``BZip2``, ``GZip``, ``XZ``, and ``Zstd``.

  .. versionadded:: 3.19
    The compression level can be specified with the ``COMPRESSION_LEVEL``
    option.  The ``<compression-level>`` should be between 0-9, with the
    default being 0.  The ``COMPRESSION`` option must be present when
    ``COMPRESSION_LEVEL`` is given.

  .. versionadded:: 3.26
    The ``<compression-level>`` of the ``Zstd`` algorithm can be set
    between 0-19.

  .. note::
    With ``FORMAT`` set to ``raw``, only one file will be compressed with the
    compression type specified by ``COMPRESSION``.

  The ``VERBOSE`` option enables verbose output for the archive operation.

  To specify the modification time recorded in tarball entries, use
  the ``MTIME`` option.

.. signature::
  file(ARCHIVE_EXTRACT
    INPUT <archive>
    [DESTINATION <dir>]
    [PATTERNS <patterns>...]
    [LIST_ONLY]
    [VERBOSE]
    [TOUCH])
  :target: ARCHIVE_EXTRACT

  .. versionadded:: 3.18

  Extracts or lists the content of the specified ``<archive>``.

  The directory where the content of the archive will be extracted to can
  be specified using the ``DESTINATION`` option.  If the directory does not
  exist, it will be created.  If ``DESTINATION`` is not given, the current
  binary directory will be used.

  If required, you may select which files and directories to list or extract
  from the archive using the specified ``<patterns>``.  Wildcards are
  supported.  If the ``PATTERNS`` option is not given, the entire archive will
  be listed or extracted.

  ``LIST_ONLY`` will list the files in the archive rather than extract them.

  .. versionadded:: 3.24
    The ``TOUCH`` option gives extracted files a current local
    timestamp instead of extracting file timestamps from the archive.

  With ``VERBOSE``, the command will produce verbose output.